LF-12 · TEACHER LESSON PLAN

Mentos and soda geyser

Why dropping Mentos into soda triggers an instant eruption

ChemistryGrades 5–925 minHazard medium; sudden soda plume and slippery spillNGSS MS-PS1-4

01 //

Driving question

START THE LESSON WITH THISHow does the number of Mentos dropped into a bottle of soda change the height of the eruption?

02 //

Learning objectives

Students plan a safe outdoor comparison using 2, 4 and 6 Mentos while matching soda brand, bottle size, temperature and drop method.
Students measure peak plume height against a marked backdrop in inches for three fresh-bottle trials at each candy amount and calculate the mean and range.
Students explain the eruption as rapid carbon dioxide bubble formation at nucleation sites, not a new chemical reaction or a pure-substance state-change test.

03 //

Standards

Dimension	Alignment
Performance expectation	MS-PS1-4Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed. (Partial alignment: the lab lists this expectation, but the eruption is mainly rapid bubble nucleation and release of dissolved carbon dioxide, not a thermal-energy change to a pure substance.)
Practices	SEP 6Construct explanations.
Core idea	PS1.AThe changes of state that occur with variations in temperature or pressure can be described and predicted using these models of matter.
Crosscutting	Cause and effectCause and effect relationships may be used to predict phenomena in natural or designed systems.

Standards text paraphrased from nextgenscience.org. Alignment is partial; this hands-on activity does not cover every part of the performance expectation.

03A //

State standards crosswalk

Use the row as a planning crosswalk, then confirm local district pacing and grade placement. “Partial” labels describe a skill connection, not full mastery of the complete standard.

State	Verified standard	How this lesson aligns	Official source
California	CA NGSS MS-PS1-2	Use the activity to distinguish physical gas release from a chemical reaction; this lab does not itself meet the reaction-analysis expectation.	Open standard ↗
Texas	SCIENCE.8.1.F	Organize repeated measurements and use means to identify patterns; directly supports three trials at each candy count.	Open standard ↗
Florida	SC.8.P.9.2	Differentiate physical and chemical changes; the lesson explicitly explains that Mentos release dissolved carbon dioxide without making a new substance.	Open standard ↗
New York	MS-PS1-2	Use the lesson's physical-versus-chemical distinction as a contrast; the eruption does not itself satisfy the chemical-reaction performance expectation.	Open standard ↗
Pennsylvania	3.2.6-8.D	Use as a contrast case when discussing physical versus chemical change; this eruption is not itself a chemical reaction investigation.	Open standard ↗

04 //

Materials and prep timeline

PER GROUP

Nine unopened bottles of one soda product, same brand and size; bring to the same starting temperature
Mentos candies in portions of 2, 4 and 6, each portion prepared three times
Rolled-paper drop tube or teacher-approved drop tool
Low freestanding marked height board; set it from ground level
Eye protection, open hoseable outdoor area, towels and timer

TEACHER ONLY

Run the eruption outdoors only on level grass or pavement that can be hosed off; keep the activity well away from anyone's face.
Require eye protection and clear the bottle opening area before each release. Students step back immediately; an adult supervises uncapped bottles and the release.
Use a fresh matching bottle for each trial, never cap or hold down an active bottle, and clean the sugary spill so the ground is not slippery.

CLASS-SIZE KIT PLANNER

One per-group kit contains every item in the team materials list above. Groups are balanced around the listed 3–4 students target.

Students	Groups	Per-group kits	Student sheets	Suggested group split
20	5	5 complete kits	20 copies	4 students per group
25	7	7 complete kits	25 copies	4 or 3 students per group
30	8	8 complete kits	30 copies	4 or 3 students per group

0–4 MINPredict and set boundaries

State the question and identify candy count as the change and peak plume height as the measure. Review outdoor-only setup, eye protection, clear faces and immediate step-back.

4–8 MINSet the scale

In an open hoseable area away from people, buildings, windows, overhangs and wires, place a low freestanding height board behind the bottle position. Match soda product, bottle size and starting temperature; prepare three portions each of 2, 4 and 6 candies.

8–18 MINRelease and measure

An adult runs each trial with a fresh bottle while everyone wears eye protection and remains behind the safe line. Drop candies together, step back immediately, then record peak height from the fixed viewing point. Run three fresh bottles per count.

18–22 MINCompare averages and spread

Calculate the mean and range of the three peak heights for each candy amount. Keep every reading visible, compare the pattern and note measurement uncertainty.

22–25 MINExplain and clean

Explain how candy surfaces help dissolved CO₂ form bubbles quickly; no new substance is created. Hose away soda and confirm the surface is not slippery.

04A //

Lab figures and data visuals

Reviewed article images support the lesson flow. Use the tables and student sheet to record actual observations; pictured patterns are not target results.

Before-and-after panels show an adult setting a low height scale from the ground before release, then everyone wearing goggles and observing from behind a barrier. — **Prepare first, then step back.**Set the low scale before the run; when the bottle erupts, everyone stays behind the safety line.

An outdoor fair-test illustration shows two fresh matching soda bottles for each of three Mentos-count conditions, with observers behind a safety line. — **Repeat both bottles for every count.**Compare 2, 4 and 6 Mentos using two fresh matching bottles at each level; record both actual peak heights without assuming which count wins.

Dissolved carbon dioxide leaves soda as bubbles and foam; the candy helps bubbles form without creating a new substance. — **Explain the gas release.**Carbon dioxide is already dissolved in the soda; Mentos surfaces help bubbles form rapidly.

04B //

Printable shopping list

TEACHER PREP · Mentos and soda geyser

Shopping and staging checklist

Multiply the per-group kit contents by the class-size planner. The teacher section includes teacher-provided materials and setup or safety notes.

PER-GROUP KITS

Nine unopened bottles of one soda product, same brand and size; bring to the same starting temperature
Mentos candies in portions of 2, 4 and 6, each portion prepared three times
Rolled-paper drop tube or teacher-approved drop tool
Low freestanding marked height board; set it from ground level
Eye protection, open hoseable outdoor area, towels and timer

TEACHER-PROVIDED MATERIALS + SETUP RULES

Run the eruption outdoors only on level grass or pavement that can be hosed off; keep the activity well away from anyone's face.
Require eye protection and clear the bottle opening area before each release. Students step back immediately; an adult supervises uncapped bottles and the release.
Use a fresh matching bottle for each trial, never cap or hold down an active bottle, and clean the sugary spill so the ground is not slippery.

Prepare 5 kits for 20 · 7 kits for 25 · 8 kits for 30 students.

05 //

Lesson flow

Minutes	What happens
0–4	Engage Ask how 2, 4 or 6 Mentos may affect peak eruption height. Identify the changed and measured variables and review the outdoor-only safety boundaries.
4–8	Explore Set a low freestanding scale in a level, open, hoseable area away from people, buildings, windows, overhangs and wires. Match soda product, bottle size and temperature; prepare three portions of 2, 4 and 6 candies.
8–18	Explore An adult runs three trials per candy amount using a fresh bottle each time. Students wear eye protection, stay behind the boundary and record from a fixed safe point after the adult steps back.
18–22	Explain Calculate each three-trial mean and range and compare the results. Explain that Mentos surfaces provide sites for dissolved carbon dioxide bubbles to form.
22–25	Evaluate Describe the eruption as a physical release of existing gas, not a chemical reaction or thermal state-change demonstration. Hose the area and remove slippery soda residue.

06 //

Discussion questions

1. Why can more Mentos make the plume taller?

SAMPLE ANSWEREach candy surface provides many sites where dissolved carbon dioxide can form bubbles. More candies can create more release sites at once, though the size of the effect depends on the bottle and release.

2. Why use a fresh bottle for every trial?

SAMPLE ANSWERThe first eruption releases gas and changes the soda, so a second candy drop in that same bottle would not start from the same condition.

3. Why calculate a mean and range from three trials?

SAMPLE ANSWERThe mean summarizes the three measured heights, while the range (highest minus lowest) shows their spread. Keep all readings visible because three trials are still a small sample.

4. Is the geyser a chemical reaction that tests MS-PS1-4?

SAMPLE ANSWERNo new substance forms: carbon dioxide was already dissolved in the soda. Mentos promote rapid bubble nucleation, so this is only partial alignment with an expectation about thermal energy and pure-substance state changes.

07 //

Common misconceptions

STUDENTS OFTEN SAY“Mentos make carbon dioxide in a chemical reaction.”

BETTER IDEAThe soda already contains dissolved carbon dioxide. The candy surface helps that gas form bubbles and escape quickly.

STUDENTS OFTEN SAY“More candies always guarantee a taller plume.”

BETTER IDEAMore nucleation sites can increase the eruption, but soda temperature, bottle, simultaneous release and measurement affect the observed height.

STUDENTS OFTEN SAY“Standing beside the bottle is fine if I look away.”

BETTER IDEAThe plume starts quickly and can spray eyes or faces. Wear eye protection, keep clear of the opening and step back immediately after release.

08 //

Differentiation

SUPPORT

Prepare labeled sets of three 2-, 4- and 6-candy portions and a backdrop scale before students enter the outdoor area.
Assign roles for candy loading, recording and height reading while everyone remains clear of the bottle opening.
Offer the frame: “With __ candies, the three heights were __, __ and __ inches; the mean was __ inches and the range was __ inches.”

EXTEND

Compare the three-trial range at each candy count and identify which amount had the most repeatable heights.
Explain why three trials still provide only a small sample of natural variation.
Design a controlled follow-up that varies soda temperature while holding candy count constant, under the same outdoor safety controls.

09 //

Assessment rubric

Criterion	Beginning	Developing	Secure
Safe controlled plan	Plans an indoor test or omits basic controls.	Works outdoors but misses a control or plume precaution.	Works outdoors, matches soda conditions, uses eye protection, keeps people clear and steps back immediately.
Peak height data	Leaves heights blank or reports no units.	Records some peak heights but misses trials or confuses the scale.	Records three peak heights in inches for each of 2, 4 and 6 candies against the backdrop.
Mean and pattern	Does not calculate a mean or compare amounts.	Calculates some means but does not show all trial values or pattern.	Calculates correct three-trial means and ranges and uses the measurements to describe the pattern and variation.
Causal explanation	Claims Mentos create a new substance or gas.	Mentions bubbles without explaining nucleation or alignment limits.	Explains release of dissolved CO₂ at nucleation sites and notes this is not a thermal state-change model of a pure substance.

10 //

Vocabulary

Carbon dioxide – A gas dissolved in a carbonated drink under pressure.
Nucleation site – A surface location where bubbles can begin forming more readily.
Plume – A rising column of liquid droplets and gas released during the eruption.

Peak height – The greatest vertical height reached by the eruption during a trial.
Mean – The sum of measured values divided by the number of values.
Controlled variable – A condition kept the same while testing the planned change.

11 //

Safety, cleanup and troubleshooting

BEFORE STUDENTS TOUCH ANYTHING

Perform the activity outdoors only on level grass or pavement that can be hosed off, well away from anyone's face. Wear eye protection and stand back immediately after dropping candies; the plume starts within about a second.
Keep everyone away from the bottle opening and plume. Do not lean over, hold down or recap the bottle; release the candies and step back without delay.
Soda makes pavement or grass slippery. Hose or wipe the area after the activity and check that no sticky spill remains before anyone walks there.

Troubleshooting: If candies do not enter together or the bottle is disturbed, mark the trial as a setup problem and use a fresh matched bottle only after the area is clear. Never retrieve candies from an active bottle or lean over its opening. If soda spills, keep people away until an adult has cleaned the surface and confirmed it is not slippery.